The ‘O-H’ bond is the functional group of alcohols. Alcohols contain a bond between O-H, where the oxygen is bonded to a carbon. This is their functional group, used in reactions.
As we have seen with alkanes and alkenes, alcohols can also be named. The first four alcohols in the homologous series are called methanol, ethanol, propanol and butanol.
Representing Alcohols
Alcohols can be represented. We can represent alkenes very easily, by using the number of carbons each molecule contains. Ethanol can be represented as CH3CH2OH.
Alcohols can be drawn out. We can also represent alcohols using their displayed formulae. For example, the displayed formulae of ethanol is shown below.
Production of Ethanol by Fermentation
Ethanol (C2H5OH) is one of the most important alcohols
It is the type of alcohol found in alcoholic drinks such as wine and beer
It is also used as fuel for cars and as a solvent
It can be produced by fermentation where sugar or starch is dissolved in water and yeast is added
The mixture is then fermented between 15 and 35°C with the absence of oxygen for a few days
Yeast contains enzymes that break down sugar to glucose
If the temperature is too low the reaction rate will be too slow and if it is too high the enzymes will become denatured
The yeast respire anaerobically using the glucose to form ethanol and carbon dioxide: